Isotherm 65 Performance Good or Bad?

manyman297

The Isotherm compressor fridge in our 400 seems to work just fine as long as outside temps stay below 90 but once things warm up past 90 the fridge temp goes from 38-40 degrees to 47+ and turning the thermostat to 7 really doesn’t do anything. The only way to get the fridge down in temp is to run the AC which is fine when we’re in the camper but during travel days or times when we’re away from the camper my guess is the fridge will be struggling to maintain temp (I discovered this on our last 1700 mile trip). 

In fact this past weekend when we camped in 96 degree weather without AC the fridge actually got up to 60 degrees at one point and stayed there well into the night. 

What can I expect in terms of performance from this fridge?

Dutch061

Okay, I believe that you brought this up in a previous post because I definitely remember mentioning the heat soak in the enclosure surrounding the refrigerator.

We have a 2020 400 BDL with the Norcold NR751BB and I decided to ventilate the compartment, not so much to improve cooling but to hopefully reduce temperatures surrounding the refrigerator and reduce the "running time per hour" that it is operating to reduce AH consumption. I have performed that modification and will show some pictures below, as of today I have only done some preliminary testing with it in the back yard, but it is about to get the 6 week road trip in 3 days. So hopefully I will have more to share afterwards. 

There is a panel at the end of the bed between the bed and the wall that must be removed to access. I have found it easiest to remove the 2 screws that hold the foot of the bed in place over the exterior compartment to make it easier to remove the first panel.

Hose removed from original battery vent, factory installs AGM and they are sealed. With AGM or Li-Ion, the battery compartment doesn't need to be vented. I suspect the battery compartment is vented is in case someone were to install Lead Acid Batteries. 



I used a hole saw with the pilot drill bit removed to cut and remove the hose adapter as shown below. It is important to note that I didn't disturb the sealant for this vent nor did I damage the original screen when I cut the adapter out. 



You can in the photo above the baffle I made to seal the bottom of the column to prevent air from being drawn other than from the enclosure around the refrigerator. Below is a better photo of the baffle.



Lastly, below is a photo of the 92 MM 12 volt cooling fan installed and the baffle, before re-installing the corner enclosure trim. I bought the fan from Amazon (where else?) and it was about $13.00




I connected the auxiliary fan to the wiring for the original cooling fan on the refrigerator, so that when the refrigerator cycles on and the original fan is running, that my auxiliary fan runs too. 

It definitely helps to remove the heat, based on my "backyard testing". I haven't really seen an improvement in cooling efficiency IE lower refrigerator internal temperatures but that wasn't my primary goal either. The Norcold NR751BB will easily hold 42 +/- 2 degrees for weeks at a time previous to this modification with or without the A/C operating. 

What remains to be seen is if it helps reduce the enclosure temperatures (which it certainly should) thereby reducing the "running time per hour" and thereby reducing the AH consumption. Even though I have 200 Ah of Battleborn, I am about to embark on 6 weeks of mostly boondock camping. I have found that previously between the 2 vent fans and the refrigerator, I was averaging 4 Amps per hour consumption or 48 to 60 in 12 to 14 hours. However, it was VERY hot outside and I had little to no shade. 

Brad

manyman297

@Dutch061 You're right. I had posted about this issue but couldn't find it

On the 2021 that vent is further toward the rear of the camper. It's still possible to use it as a vent but it would be an undertaking running tubing from the fridge compartment.

I also wonder if installing a fan near the Alde vent in the countertop would at least help move the warm air behind the fridge out into the living space. Not as good as moving it outside but still better than its current setup.

Doesn't the 320 have a vent above the fridge? Is that for the fridge or something else?

I'll be interested to see how your mod works in the wild.

Dutch061

Since I haven't actually seen a 2021, I am not familiar with the vent you are referring to.

I believe on the 2016 and earlier 320's, the there were a couple of vents on the front of the camper to aid in cooling the 3 way refrigerator installed.

I too am interested to see if my modification helps, it became much more expensive than the $13.00 fan, but I will save that story for another time.

Brad

manyman297

I also wonder if upgrading the fan on the actual fridge would help any. I’m not sure what the specs are on the stock fan but my guess is you could install a new fan with a higher CFM. That would be something I’d consider once the warranty is up. I may start with installing a fan towards the countertop vents and see if that does anything. 

Dutch061

You could also possibly add holes and fans to the exterior of the cabinet to aid in getting the heat out. Unfortunately as you already mentioned, that heat will end up inside the camper, but probably no real difference than how it is now as far as adding heat to the interior of the camper.

I guess the hopeful outcome would be to reduce the heat "in the box" that holds the refrigerator with the anticipation that it would run less and create less heat in the end.

Again, since I have not seen a 21, I can't speak intelligently to this suggestion.

Brad

manyman297

I've pulled the fridge before and the cabinet has a long "vent" in the bottom of it (so it's pulling air from the drawer underneath the fridge) and the vents in the countertop where heat exits. I don't believe it has the large hole in the right side of the cabinet that the 2020s have. Looking at the manual for the fridge it has venting requirements for the bottom left side of the unit...so maybe that's where the issue is. I could easily drill a 3" hole (the size the manual states) and give it ventilation from the adjacent cabinet.

Dutch061

It is my belief (although still untested) that anything that you can do to reduce the heat around the refrigerator in the cabinet will provide better cooling and less running time per hour.

Although, as mentioned "untested" and I could be very wrong. I will have an update in a few weeks. Even though we are heading for cooler weather and higher ground, there is still some warm places to travel through on the way there.

Brad

manyman297

So I used my FLIR camera to see just how hot it gets behind the fridge compartment. It was about 95 degrees yesterday so it was a good test. I had the vent fan on 50% with the door open to help cool the cabin. Even then the temps behind the compartment got up to 111 degrees.

Interestingly the compartment was at 88 degrees before the fridge was turned on which shows how much heat is generated by the fridge. Also, the stove and countertop actually get warm as well.

Long story short, I think this compartment just needs to be ventilated better. @Dutch061 Have you been able to test your vent mod?
Temp before turning fridge on.


Temp after fridge was on for a few hours. Granted the exterior temperature did increase but maybe by 5-10 degrees but the door was open and fan on as well.